BACKGROUND Aim of the present study was to assess the efficacy and trainability of intensive training programs based on plyometrics and strength conditioning over two successive seasons compared to habitual routines. METHODS Nine female gymnasts following typical elite training routines (30 h per week) volunteered for this study. They performed the following jump tests on the same day: 1) squat jump with progressive loads of 0%, 25%, 50%, 75% and 100% of body mass (SJ0-25-50-75-100); 2) counter movement jump (CMJ); and 3) counter movement jump with arm swing (CMJA). Flight time (FT), and FT with respect to body mass (FTbm) were the parameters analysed. This study was based on a 20-month longitudinal design covering two training seasons. Each season included one control and one experimental period (CtrlΔ1 + ExΔ1 and CtrlΔ2 + ExΔ2 respectively), with jump assessment at the beginning and end of each period. The gymnasts demonstrated a significantly greater improvement of jump performance during the two experimental periods than in the respective control periods. RESULTS Results confirm the detraining phenomenon after ExΔ1 and indicate that when the girls reach a very high level of jumping performance, it is very difficult to maintain this. The contractile component (CC) improved much more during the two experimental periods than during their respective control periods. In contrast the elastic component (EC) and arm participation (AP) did not change significantly during the two-season monitoring. CONCLUSION On the basis of our findings, we suggest that it is worthwhile to reduce the time spent on technical routines on apparatus and that 2-3 intense physical conditioning workouts be introduced to optimize gymnasts' jumping skills.